3.4. What are the goals of nutritional/fluid therapy

The goals of parenteral support are to correct nutritional status, and to maintain fluid and electrolyte balance, in order to optimize quality of life.

The overall aim of parenteral support is to restore and maintain nutritional adequacy and thus to help achieve a good/normal quality of life. This is partly met by restoring or maintaining a normal body weight and growth/sexual maturation in children. It also involves achieve hydration (salt and water balance) and a normal serum (red blood cell) magnesium. There should be no vitamin or micronutrient deficiencies. These goals are achieved in conjunction with consideration of the patient’s height, weight, and usual weight in health/desired body weight. A target weight can usually be set and an appropriate amount of energy given to meet this over an appropriate interval. Asking about thirst, measuring postural systolic blood pressure and measuring random urine sodium concentration all help to assess hydration.116

Since the connection to a central line impairs the mobility and quality of life of the patients, parenteral regimens should be designed to be provided on as few nights as possible but still to ensure correct fluid balance. This can be difficult if there are high stomal fluid losses. Even then it may be better to have intravenous fluids only (no nutrition) on some days, since they can generally be given more quickly than high osmolality nutritional admixtures. In general PN is given overnight so the patient can appear normal during the day and may go to work or undertake other duties and activities. Some use portable pumps and infuse during the day, which may also be more physiological. It can be difficult for patients to take normal meals, as they may have to regularly empty their stoma bags. Sometimes taking no fluid for half an hour before and after food can reduce the sudden high output with food even if it does not reduce the total daily stomal output. More details are given in the ESPEN guidelines on Home Parenteral Nutrition.

3.5. Do patients require specific substrate (PN) composition?

PN composition must be adjusted to fulfill the needs of the individual single patient. This will depend on the extent of malabsorption, and enteric losses, and will influence the prescription of energy and amino acids, and especially of water, electrolytes and minerals [B]. Each PN cycle (usually nocturnal) should be complete and adjustment will be made on the number of cycles per week [C]. PN, especially at home, should be viewed as complementary non-exclusive nutrition, which can be tapered to a minimal level when body composition has been sufficiently restored. Currently, no specific substrate composition is mandated per se, but every micronutrient should be given in order to avoid deficiency and to promote protein/energy efficiency [B].

Comments: Energy and protein: 2/3 of calories as glucose and 1/3 from lipid emulsion ( 20%) seems a good compromise. No more than 1 g/kg/day of standard lipid emulsions can be recommended, because greater amounts prove a significant independent factor for chronic cholestasis and progression through liver fibrosis to cirrhosis, even in the optimal case of ‘‘normonutrition’’.117 Total energy (including protein) should comprise between 0.85 and 1.5 times the REE. Nitrogen needs should be given as amino acids at

1–1.5 g/kg/day, to take into account increased digestive protein losses.118,119 Ideally, digestive balance, either negative or positive110,120,121 has to be summated with the IV infusion to reach the

final level of the needs [IIA]. The second adjustment is achieved with the attempt to decrease the number of IV infusions per week;

indeed the patient usually prefers, for obvious QOL reason, a minimum number of ‘‘complete’’ IV infusions per week.122

Gastrointestinal fluid balance (enteral fluid intake less stomal or stool output(s)) should be more than about 1.4 kg/day to be confident that the patient will not be dependent on parenteral support for hydro-mineral reasons.121 In general a gastrointestinal output of more than 1.4 kg has similar significance. Around 20% of SBS patients remain dependent on parenteral supplies of water and sodium but become independent of parenteral protein and energy; this is especially the case in end-jejunostomy patients.120 Then, water and sodium input should be given to obtain positive balances (avoid dehydration, tiredness, masked hypokalemia) and tailored according to each individual’s needs, independently of protein energy needs.

For other nutrients, old studies have demonstrated that every mineral and most of the vitamins and trace metals (especially zinc) have to be in positive balance(s) to promote nitrogen retention.123 Furthermore, dramatic clinical deficits were recognized in the pioneering era of HPN, when vitamin(s) or trace metal(s) had been omitted for various periods of time (from weeks to months) (see ESPEN HPN guidelines). It is accordingly recommended that total micronutrient requirements should be given via the IV route [B]. Some of them should be given in increased amounts because of the increased digestive losses (e.g., zinc, magnesium). Special effort

should be made to avoid magnesium deficit given the interactions with sodium, potassium and calcium negative balances112,113 [IIA].

Recently, pseudo gout has been demonstrated as being significantly associated with hypomagnesemia during HPN.124

3.6. What role does PN have in short bowel?

3.6.1. Post-operative phase

In the early phase after massive enterectomy, the main goal is to assure hemodynamic stability by providing water and electrolytes (e.g., intravenous normal saline or a balanced electrolyte solution such as Hartman or Ringer solution, 1–4 l/day, depending upon intestinal losses) [B].

Most patients with a short bowel require parenteral nutrition for the first 7–10 days after the resection but not necessarily in isolation [C].

Comments: In the early phase after massive enterectomy, the immediate goals are survival and hemodynamic stability aided by the provision of water and electrolytes. Nutritional therapy should not be introduced until the patient is hemodynamically stable.

To avoid sodium and water depletion from the stomal losses in patients with a jejunostomy it is easiest to rehydrate with mainly intravenous normal saline (2–4 l/day) while keeping the patient ‘‘nil by mouth’’125 [IIb]. After 1–2 days, oral food and restricted oral liquid are progressively introduced. The aim is to maintain good hydration status with a urine volume of at least 800–1000 ml with a random urine sodium concentration greater than 20 mmol/l.114 Blood glucose concentration must be monitored at least daily while on PN and should be below the actual recommendations for acutely ill patients. There is currently no evidence for providing intravenous glutamine in order to increase intestinal adaptation.

Many patients with a short bowel require parenteral nutrition for the first 7–10 days. However, parenteral nutrition should not be started until the patient is hemodynamically stable and fluid/ electrolyte balance has been reached [B]. Patients should receive about 25–33 kcal/kg and 1–4 l/day depending upon stomal/stool losses. Intravenous lipids should account for 20–30% of infused calories but may be increased in the short-term in the case of glucose intolerance. After 2 weeks the frequency of lipid administration may be reduced to 1–2 times a week to reduce the risk of

cholestasis [C]. Enteral nutrition should be initiated and progressively increased depending on the gut tolerance; a standard enteral diet is recommended if a colon is present in continuity. If a jejunostomy is present the enteral feed needs to be of lower osmolarity (e.g., around 300 mOsm/kg) and contain at least 100 mmol/l of sodium [A].

Initially, H2-antagonists or proton pump inhibitor (PPI) are started (and typically continued for six months) because acid hypersecretion may occur, even if there is a lack of direct evidence in man. The pH of the stomal output can be checked and should be >6 if adequate PPI is being absorbed. In the early stage, intravenous administration may be needed as the absorption of oral medicine may not be predictable. Acid suppression has the other important effect of reducing gastric fluid secretion, but may also prevent deconjugation of bile salts and may decrease endogenous pancreatic lipase excretion.

Loperamide hydrochloride or diphenoxylate reduce intestinal motility and intestinal losses by approximately 20–30%.126,127

Typical doses of loperamide are 4 mg taken four times a day. If not effective, codeine phosphate (30–60 mg, 2–4 times daily) or tincture of opium may be necessary. In some cases, the effect of loperamide and opiate drugs both together may be greater. These drugs must be taken half an hour before food.

In adults, octreotide significantly reduces daily jejunostomy output (though may be no better than omeprazole). The greatest reductions in intestinal output are in those with a net secretory output. The volume of intravenous fluids may be reduced. Long

acting octreotide/somatostatin preparations have not been assessed in large studies.128–130 A recent small study with the long-

active derivative of octreotide showed no benefit.131 Long-term use of octreotide could reduce splanchnic protein synthesis, thereby reducing mucosal protein incorporation and villus growth rate. It could also increase the risk of cholelithiasis formation in patients with short gut.

3.6.2. Adaptation phase

Appropriate enteral and/or oral nutrition should be initiated as soon as possible and progressively increased depending on the tolerance of the gut and the patient.

Special attention must be paid to sodium, potassium and magnesium balance. Oral hydration in patients with a jejunostomy should include a glucose–saline replacement solution (with a sodium concentration of 90 mmol/l or more) [A].

In patients with a jejunostomy (and indeed in some with a retained colon) it is important to restrict the use of oral hypotonic drinks (tea, coffee, juices, beer, etc.) which cause sodium loss from

the gut, and of hypertonic solutions that may contain sorbitol or glucose which cause both sodium and water loss132,133 [IB]. Patients

should be encouraged to drink a glucose–saline replacement solution (sodium 90 mmol/l or more). Several commercially available oral rehydration solution (ORS) formulas are available; although probably the best is that hitherto recommended by the World Health Organization (WHO) (the potassium chloride component can be omitted). Patients with a short bowel should be cautioned against consumption of plain water and should be invited to drink ORS whenever they are thirsty. The patients should be encouraged to sip these ORS solutions in small quantities all day long (cold with flavoring may make the solution more palatable).134

Patients with stomal losses of less than 1200 ml daily can usually maintain sodium balance by adding extra salt135 [IIA]. Large amount of sodium chloride (8–14 capsules of 500 mg each) are effective but may provoke digestive intolerance with vomiting. Attention must be paid to the magnesium balance. In addition to

sodium losses, significant losses of magnesium occur in the intestinal effluent and in the urine. Given that important magnesium deficiency may develop despite a normal serum magnesium concentration, it is ideal to measure 24-h urine magnesium loss.136 Magnesium deficiency may be associated with: (a) calcium defi-

ciency because hypomagnesemia impairs parathyroid hormone release137,138; and (b) potassium deficiency because hyper-

aldosteronism (from sodium depletion) increases renal retention of sodium at the expense of magnesium and potassium which are lost in high amounts in the urine. Oral supplementation of magnesium (often with 1-alpha calciferol) is not always successful and intravenous supplementation may be required112 [IIA]. To correct hypokalaemia in patients with a high output stoma, sodium/water depletion must first be corrected to avoid hyperaldosteronism, and serum magnesium should also be brought into the normal range.

3.6.3. Maintenance/Stabilization phase

According to the length of residual small bowel as well as the type of anatomy (preserved colon or not), patients with short bowel may need long-term parenteral nutrition [B]. In some of them, the main problem is related to stabilizing their water and electrolyte balance. In some (usually with a retained colon) appropriate adaptive hyperphagia, and intestinal adaptation may improve nutritional status sufficiently that PN can be reduced or stopped [B].

Comments: Measurement of intestinal absorptive capacity is beneficial when considering dietary treatment of the individual short bowel patient.114 Patients can be categorized as having problems with sodium or protein–energy balance, or both, and balance studies may quantify the degree of intestinal insufficiency.121 This enables the physician to identify patients with suspected irreversible intestinal failure, either due to sodium or energy malabsorption, and those in whom dietary manipulations alone are more justifiable. Recommendations are always dependent upon remaining intestinal physiology.

The consequences of dietary manipulations, however, not only on nutrient, electrolyte and fluid absorption, but also on overall quality of life, must be taken into consideration when guiding short bowel patients.119 Dietary manipulations may affect the palatability of food and the sense of satiety, which may be of importance when encouraging the patients towards an increased energy intake. Dietary manipulations may also affect abdominal sensation; discomfort, bloating and passing of air are common in this context, and changes in fecal consistency and fecal incontinence may seriously impair quality of life. The patient’s autonomy should be respected and nurtured by efforts of physicians and dieticians in support of the patient who faces intestinal failure. Some patients prefer the hyperphagia, large stool volumes, fatigue and chronic dehydration in order to avoid a life tied to a central line and parenteral supplements110 [IIa]. Others see parenteral supplements as a place of refuge escaping the demands of constant hyperphagia and concomitant large stool volumes and abdominal discomfort. Balance studies should not only be seen as tools of studying intestinal physiology in the short bowel syndrome, but they also give the individual patient a chance to experience the effect of extreme diets on fluid and energy absorption and on their well being.139 Optimal

nutritional care, guidance and support are of vital importance in the long-term management of the chronic short bowel syndrome.140,141

In patients with a preserved colon a high-carbohydrate, low (not increased) long-chain triglyceride diet is recommendable, and medium-chain triglycerides may be of benefit. A low oxalate diet with calcium supplements before meals is recommended to reduce the risk of calcium oxalate renal stone formation.